Authorities in Pakistan have held three people over a threat to bomb a church school in Islamabad unless it paid them $51,000 (£38,000), officials say.
A letter sent to the school, apparently by a little-known militant group, demanded cash for not bombing it.
It accused the church school of offering prayers for Pakistani schoolgirl Malala Yousafzai, who was injured by a Taliban gunmen in October.
Correspondents say this is being taken seriously by Pakistani intelligence .
The letter was received by the school in November and intelligence officials are still investigating.
It warned the church administration that they would be “responsible for the consequences” if they reported the cash demand to the authorities.
The three arrests were made in Khyber Pakhtunkhwa province, police say.
The BBC’s Shahzad Malik in Islamabad says that the letter was sent by a previously unknown group called the Khyber Pakhtunkhwa Suicide Attackers Group.
Our correspondent says that while the Pakistani Taliban generally assumes responsibility for militant attacks, insurgent groups operating in the field often chose a variety of different names.
There are numerous instances where these groups have carried out attacks claimed by the Pakistani Taliban, our correspondent says.